JPS59183256A - Air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an air conditioner for both cooling and heating, which forms a refrigeration cycle using an electric expansion valve that adjusts its valve opening according to an electric signal as a pressure reducing device. It is.

<Prior art> In a conventional refrigeration cycle for both heating and cooling, a compressor, a four-way switching valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger are sequentially connected in a ring shape, and during cooling operation, high droplets from the compressor are removed. High-pressure refrigerant gas is sent to the outdoor heat exchanger, where it is condensed and then evaporated in the indoor heat exchanger via an expansion device. During heating operation, the high-temperature, high-pressure refrigerant gas from the compressor is reversely circulated for heating. When performing defrosting during heating operation, high-temperature, high-pressure refrigerant gas is flowed to the outdoor heat exchanger by switching the four-way switching valve, which naturally exchanges heat with the frost that has adhered to the exchanger.
It is designed to melt and remove frost, but when this four-way switching valve is switched, the liquid refrigerant is switched while still being at high pressure, so a high-pitched refrigerant gas sound is generated, and the high pressure that was in the indoor heat exchanger is The liquid refrigerant flows back into the compressor and accumulates in the accumulator to prevent liquid compression, and the amount of refrigerant circulating in the refrigeration cycle is insufficient, so sufficient defrosting cannot be performed. This has the disadvantage that defrosting takes a long time, lowers the room temperature, and impairs comfort.

Purpose of the present invention The purpose of the present invention is to solve the above-mentioned technical problem, and to remove frost on an outdoor heat exchanger during winter, etc., when switching the operation of an air conditioner from heating operation to cooling operation, To provide an air conditioner that prevents the generation of refrigerant gas noise and prevents backflow of liquid refrigerant to a compressor to perform efficient operation. <Examples> Examples of the present invention will be described below with reference to the drawings.

Figure 1 shows the configuration of a refrigeration cycle, where 1 is a compressor, 2 is an outdoor heat exchanger, 3 is an electric expansion valve, 4 is an indoor heat exchanger, 5 is a switching valve, and 6 is an electric expansion It is a valve control circuit,
Temperature detectors 6A and 6B provided at the inlet of the heat exchanger 2.4 and a temperature detector 6 provided in the suction pipe of the compressor 1
CK: Expansion valve 3 so that the detected temperature difference is constant.
It outputs an electrical signal to control the

Three electric expansion valves are used here, and an electric expansion valve whose opening degree is adjusted by a stepping motor is used, and the electric expansion valve is configured as shown in Figure 2. .

7 is a stepping motor, 8 is a drive screw that converts the rotational motion of the motor 7 into reciprocating motion, 9 is a valve, and 10 is a valve seat.
By moving the valve 9 up and down, the distance between the valve 9 and the valve seat 10 is adjusted to adjust the amount of pressure reduction.

In addition, instead of this electric expansion valve, a thermoelectric type that adjusts the deformation of the bimetal by heating with a heater and thus adjusts the valve opening, or a magnetic attraction force of a solenoid is used. An electric expansion valve such as an electromagnetic type may also be used.

Here, the operation of the compressor 1, expansion valve 3, and switching valve 5 during defrosting will be explained according to the control chart diagram shown in FIG. 3.

When defrosting is started at time to, first, the compressor 1 is stopped, and at the same time, the control circuit 6 controls the valve opening of the expansion valve 3 to be fully open. Next, at time tl, when the time required for pressure balance has elapsed, the switching valve 6 is switched, and the opening degree of the expansion valve 3 is returned to the appropriate valve opening degree during defrosting operation, and the compressor 1 is restarted. Then, at time t2 when defrosting is completed, the compressor 1 is stopped and the expansion valve 3 is fully opened again, and at time t3, after the time required for pressure balance has elapsed, the switching valve 5 is switched to open the expansion valve again. 3 to return to normal control,
Start compressor 1. In this way, since the control circuit 6 controls the expansion valve 3 to fully open when the compressor 1 is stopped, the time required for pressure balance between the high pressure side and the low pressure side is shown by the solid line in Figure 4. As shown, the time is significantly shortened compared to the conventional device shown by the broken line. In FIG. 4, the horizontal axis shows the passage of time, the vertical axis shows the horizontal pressure, the solid line A shows the pressure change on the high pressure side according to the present invention, the solid line B shows the pressure change on the low pressure side according to the invention, and the broken line C shows the pressure change on the conventional high pressure side, and the broken line shows the pressure change on the low pressure side according to the invention. represents the conventional pressure change on the low pressure side.

Effects> As described above, according to the present invention, during defrosting operation, the compressor is first stopped, the expansion valve is fully opened to balance the pressure of the liquid refrigerant in a short time, and then the switching valve is switched to perform defrosting. Because of the operation, when the switching valve is switched, the pressure difference between the liquid refrigerant is almost eliminated, and the generation of loud refrigerant noise can be eliminated. In addition, the time required for pressure balance is shortened, which shortens the defrosting time, and defrosting is performed efficiently without the high-pressure liquid refrigerant flowing back into the compressor, resulting in less room temperature drop during defrosting. This makes it possible to provide air conditioning with excellent comfort.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the refrigeration cycle of the present invention, Fig. 2 is a block diagram of the electric expansion valve used in the present invention, and Fig. 3 is a control diagram of the compressor, electric expansion valve, and switching valve of the present invention. Operation diagram,
FIG. 4 is a pressure balance characteristic diagram of the present invention and a conventional device. 1 compressor, 2 indoor heat exchanger, 3 electric expansion valve,
4 is an indoor heat exchanger, 5 is a switching valve, and 6 is a control circuit.

Claims (1)

[Claims] 1. A compressor, an indoor heat exchanger, an outdoor heat exchanger,
Refrigeration consists of a switching valve that switches high-pressure refrigerant from the compressor between sending it to the indoor heat exchanger and sending it to the outdoor heat exchanger, and an electric expansion valve whose opening degree can be adjusted by an electric signal. An air conditioner characterized by comprising a control means for controlling the compressor to stop and the electric expansion valve to fully open when switching the switching valve in the cycle.